Rural mobile-money interoperability fee waivers and women's cross-border petty-trade margins in Ugandan border sub-counties: a difference-in-differences estimation of waiver-eligibility thresholds

The unresolved problem is that waiver schemes are typically evaluated at the level of aggregate transaction volumes, which obscures the discontinuous relationship between a trader's monthly transfer value and her eligibility for the waiver. Because petty traders cluster near the cutoff, the model predicts that small changes in the threshold produce discontinuous changes in net margins, and that the direction of the effect depends on whether the fee saving exceeds the incentive to inflate transfer values. The paper specifies a difference-in-differences design that exploits staggered threshold revisions across border sub-counties, defines the estimand as the local average treatment effect at the cutoff, and derives the identifying assumptions, the required panel structure and the threats to inference. The contribution is a threshold-centred framework that reframes waiver evaluation away from average treatment effects and toward the distributional consequences of cutoff placement. The paper concludes that waiver design is a distributional instrument, not merely a transaction-cost instrument, and that threshold placement determines which women benefit.